1. Data Structures and Algorithms
Prof. Ajit A. Diwan
Prof. Ganesh Ramakrishnan
Prof. Deepak B. Phatak
Department of Computer Science and Engineering
IIT Bombay
Session: Media Player Program
Ajit A. Diwan, Ganesh Ramakrishnan, and Deepak B. Phatak, IIT Bombay

2. Data Structures Structure: ‘song’
Stores information of song (ID, title, singer, and duration)
List: ‘playlist’
It is of type structure ‘song’
Iterator ‘it’
‘it’ points to a song in the playlist
Modified by incrementing/decrementing based on the functions
Ajit A. Diwan, Ganesh Ramakrishnan, and Deepak B. Phatak, IIT Bombay

3. Functions Function 1: openPlayer
Initializes the playlist by making the iterator point to the beginning of the list
Function 2: addToPlaylist
Adds the song to the playlist.
Contains title, singer, and duration of the song.
Unique ID is generated for each song that is added to the playlist
Function 3: removeFromPlaylist
Removes the song mentioned from the playlist
Ajit A. Diwan, Ganesh Ramakrishnan, and Deepak B. Phatak, IIT Bombay

4. Functions Function 4: goToFirst
Iterator points to the first song in the playlist
Function 5: goToLast
Iterator points to the last song in the playlist
Function 6: goToPrev
Iterator points to the previous song in the playlists
Function 7: goToNext
Iterator points to the next song in the playlist
Function 8: goToSong
Iterator points to the desired song in the playlist
Ajit A. Diwan, Ganesh Ramakrishnan, and Deepak B. Phatak, IIT Bombay

5. Functions These five functions (4 to 8), respectively return
True: if the function was successfully performed
False: if the function was not performed.
e.g., if iterator ‘it’ already points to first song in the list,
then ‘goToFirst’ or ‘goToPrev’ cannot be performed
e.g., if iterator ‘it’ already points to the last song in the list,
then ‘goToLast’ or ‘goToNext’ cannot be performed
Ajit A. Diwan, Ganesh Ramakrishnan, and Deepak B. Phatak, IIT Bombay

6. Functions Function 9: reverse
Reverses the list of songs in the playlist
Function 10: sortTitle
Sorts the list of songs in the playlist,
based on the title (in ascending order)
Function 11: sortDuration
based on the duration (in ascending order)
Ajit A. Diwan, Ganesh Ramakrishnan, and Deepak B. Phatak, IIT Bombay

7. Functions Function 12: displayPlaylist
Displays the list of songs in the playlist
Function 13: displaySong
Displays the song which is currently being pointed at i.e. ‘it’
Ajit A. Diwan, Ganesh Ramakrishnan, and Deepak B. Phatak, IIT Bombay

8. Stucture and class class mediaPlayer { struct song { private: int id;
song s;
static int songID;
list<song> playlist;
list<song>::iterator it;
public :
//Functions are given on the next slide
struct song {
int id;
string title;
string singer;
float duration;
}; //End of structure
Ajit A. Diwan, Ganesh Ramakrishnan, and Deepak B. Phatak, IIT Bombay

9. Functions void openPlayer();
void addToPlaylist(string songName, string singer, float duration, int position);
bool goToFirst(); bool goToLast();
bool goToPrev(); bool goToNext();
bool goToSong(string title);
void reverse();
void sortTitle(); void sortDuration();
void removeFromPlaylist(string songName);
void displayPlaylist(); void displaySong();
}; //End of class
int mediaPlayer::songID=0;
Ajit A. Diwan, Ganesh Ramakrishnan, and Deepak B. Phatak, IIT Bombay

10. Functions void mediaPlayer::displayPlaylist(){
cout << " \n";
cout << "Song Title \t\t\t Singer \t Duration\n";
list<song> copyPlaylist; list<song>::iterator copy_it;
copyPlaylist = playlist; copy_it = copyPlaylist.begin();
for (copy_it=copyPlaylist.begin(); copy_it!=copyPlaylist.end(); copy_it++)
cout << copy_it->title << "\t\t" << copy_it->singer << "\t\t"
<< copy_it->duration << endl;
cout << " \n\n";
} //End of function
Ajit A. Diwan, Ganesh Ramakrishnan, and Deepak B. Phatak, IIT Bombay

11. Functions void mediaPlayer::displaySong(){
cout << it->title << "\t\t" << it->singer << "\t\t" << it->duration << endl;
} //End of function
void mediaPlayer::openPlayer() {
it = playlist.begin();
} //End of function
Ajit A. Diwan, Ganesh Ramakrishnan, and Deepak B. Phatak, IIT Bombay

12. Functions
void mediaPlayer::addToPlaylist(string songName, string singer, float duration, int position) {
s.id = ++songID; s.title = songName; s.singer = singer; s.duration = duration;
int i; list<song>::iterator copy_it; copy_it = it;
//Insert song at specified position
it = playlist.begin();
if (position <= playlist.size()) {
for(i=0;i<position;i++) {
it++; }
playlist.insert(it,s);
else //insert at the end as position is greater than the number of songs in the playlist
playlist.push_back(s);
//Code for retaining the original position is given on the next slide
Ajit A. Diwan, Ganesh Ramakrishnan, and Deepak B. Phatak, IIT Bombay

13. Functions //Code to retain the original position
if (playlist.size()==1) {
it = playlist.begin(); //It is the only song in the playlist }
else {
it = copy_it; //Original position
} //End of function
Ajit A. Diwan, Ganesh Ramakrishnan, and Deepak B. Phatak, IIT Bombay

14. Functions bool mediaPlayer::goToFirst() {
if (playlist.size()==0 || it==playlist.begin())
return false;
else {
it = playlist.begin();
return true; }
} //End of function
bool mediaPlayer::goToPrev() {
if (playlist.size()==0 || it==playlist.begin())
return false;
else {
it--;
return true; }
} //End of function
Ajit A. Diwan, Ganesh Ramakrishnan, and Deepak B. Phatak, IIT Bombay

15. Functions bool mediaPlayer::goToLast() { if (playlist.size()==0)
return false;
if (++it == playlist.end() ) {
it--; //Point to the last song }
else {
it = playlist.end();
return true;
} //End of function
bool mediaPlayer::goToNext() {
if (playlist.size()==0)
return false;
it++;
if (it != playlist.end())
return true;
else { //It is end of the playlist
it--; //Point to the last song }
} //End of function
void mediaPlayer::reverse() {
playlist.reverse();
} //End of function
Ajit A. Diwan, Ganesh Ramakrishnan, and Deepak B. Phatak, IIT Bombay

16. Functions bool mediaPlayer::goToSong(string title) {
if(playlist.size()==0) //No song in playlist
return false;
int i; list<song>::iterator copy_it; copy_it = it;
it = playlist.begin();
while(it!=playlist.end()) {
if (title.compare(it->title)==0)
return true;
it++; }
it = copy_it; //Since song was not found, restore the original position
} //End of function
Ajit A. Diwan, Ganesh Ramakrishnan, and Deepak B. Phatak, IIT Bombay

17. Functions struct removeSong { string title;
bool operator() (const song& s) {
return (s.title.compare(title)==0); }
}; //End of structure
void mediaPlayer::removeFromPlaylist(string songTitle) {
removeSong rs;
rs.title=songTitle;
playlist.remove_if(removeSong(rs));
} //End of function
Ajit A. Diwan, Ganesh Ramakrishnan, and Deepak B. Phatak, IIT Bombay

18. Functions bool byTitle(song first, song second) {
return first.title < second.title;
} //End of function
void mediaPlayer::sortTitle() {
playlist.sort(byTitle);
} //End of function
bool byDuration(song first, song second) {
return first.duration < second.duration;
} //End of function
void mediaPlayer::sortDuration() {
playlist.sort(byDuration);
} //End of function
Ajit A. Diwan, Ganesh Ramakrishnan, and Deepak B. Phatak, IIT Bombay

19. Functions int main() { mediaPlayer player; player.openPlayer();
player.addToPlaylist("Mera joota hai japani","Mukesh ",4.2,0);
player.addToPlaylist("Gore rang pe naa itna","Kishore Kumar",4.3,1);
player.addToPlaylist("Kya hua tera vaada","Mohd. Rafi",4.8,0);
player.addToPlaylist("Kabhi Khushi Kabhi Gham","Lata Mangeshkar",4.1,53);
player.addToPlaylist("Aao huzoor tumko","Asha Bhosle",3.9,2);
cout << "Playlist:\n";
player.displayPlaylist();
Ajit A. Diwan, Ganesh Ramakrishnan, and Deepak B. Phatak, IIT Bombay

20. Functions
if (player.goToSong("Aao huzoor tumko")) player.displaySong(); else cout<<"Song not found\n";
if (player.goToFirst()) player.displaySong(); else cout << "Cannot navigate to 1st song\n";
if (player.goToLast()) player.displaySong(); else cout << "Cannot navigate to last song\n";
if (player.goToNext()) player.displaySong(); else cout << "Cannot navigate to next song\n";
if (player.goToPrev()) player.displaySong(); else cout << "Cannot navigate to Previous song\n";
if (player.goToNext()) player.displaySong(); else cout << "Cannot navigate to next song\n";
if (player.goToFirst()) player.displaySong(); else cout << "Cannot navigate to 1st song\n";
if (player.goToPrev()) player.displaySong(); else cout << "Cannot navigate to previous song\n";
Ajit A. Diwan, Ganesh Ramakrishnan, and Deepak B. Phatak, IIT Bombay

21. Functions cout << "Playlist reversed\n";
player.reverse(); player.displayPlaylist();
cout << "Playlist Sorted on Title\n";
player.sortTitle(); player.displayPlaylist();
cout << "Playlist Sorted on Duration\n";
player.sortDuration(); player.displayPlaylist();
cout << "Song Gore rang pe naa itna removed from the list\n";
player.removeFromPlaylist("Gore rang pe naa itna"); player.displayPlaylist();
return 0;
} //End of main
Ajit A. Diwan, Ganesh Ramakrishnan, and Deepak B. Phatak, IIT Bombay

22. Thank you
Ajit A. Diwan, Ganesh Ramakrishnan, and Deepak B. Phatak, IIT Bombay